1. Field of the Invention
The present invention relates to a microphone, and more particularly, to a microphone that includes a polymer waveguide that modulates a light signal to be proportional to receive acoustic energy and a receiver that converts the modulated light signal into a corresponding electrical signal that is indicative of the received acoustic energy.
2. Background of the Invention
Microphones are commonly used in a wide variety of applications, for example in the transmitters of land-line telephones and cell phones, in the broadcast, recording and entertainment industries, in auditoriums or conference rooms, and other locations where persons make public appearances or speeches. A typical microphone includes a membrane that is mounted adjacent a cavity in an acoustic housing. A capacitor and an amplifier circuit are coupled to the membrane within the housing. When acoustic energy is received through the cavity, it causes the membrane to vibrate. As the membrane vibrates, the charge on the capacitor is proportionally altered. The amplifier amplifies the varying charge, generating a corresponding electrical signal that is indicative of the received acoustic energy.
There are a number of problems associated with known microphones, such as that described above. They tend to be sensitive to radio frequency (RF) noise. This is particularly problematic with cell phones for example, where RF signals are being transmitted and received. There is also no way to filter or otherwise reduce the amplification of ambient noise. The thickness of the acoustic housing can also be a problem in certain applications. Again, using cell phones as an example, manufacturers are continually striving to provide consumers with smaller and thinner cell phones. The thickness of the acoustic housing used for the microphone may therefore be a limiting factor in how thin cell phones can be made.
A microphone that is not susceptible to RF noise and that can be fabricated to be very thin is therefore needed.